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Insights The Vacuum Fluctuation Myth - Comments

  1. Jan 11, 2017 #161

    rubi

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    None of these questions make sense.

    Please don't just type "virtual particle" into the search field of your PDF viewer and randomly quote sentences. If you had read Abhay's article, you would have seen that he is talking about a completely different theory and not about LQG. And he explains that this different theory was not successful. Moreover, even if it was, the Arnold's comments would still apply to it.
     
  2. Jan 11, 2017 #162
    Well, so almost every textbook on QFT imply "they are all wrong"... Have you taken any course in quantum field theory? Because as far as I can see, only people who haven't have issues with what A. Neumaier wrote in his insights. All those who really learnt QFT during their studies agree with what he wrote. That's weird, isn't it?
     
  3. Jan 11, 2017 #163
    Oh really then he can answer my concerns on these branches of physics and how more than a few physicists state virtual particles are real and not just internal lines.

    Considering he is specifically stating they are wrong to do so. That's not an unreasonable request
     
    Last edited: Jan 11, 2017
  4. Jan 11, 2017 #164

    OmCheeto

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    That was me he was quoting.

    I can assure you, that I have no "theories" of my own.
    I would describe my thoughts as; "hmmmmmm..... Perhaps these quantum physicists can visualize extra dimensions, which we mere mortals, can not".

    Have you ever seen this video?



    Things don't make sense, when seen in two dimensions, when they are three dimensional.
    I imagine that Quantum Mechanics, being hyper-dimensional, IMHO, is kind of like that.

    ps. The ":rolleyes:" at the end of my comment should have clued you in that his actions, were totally understandable. :smile:
     
  5. Jan 11, 2017 #165
    So Neumaiur are you going to address the issue that although an individual virtual particle doesn't cause action a group of virtual particles can ?
    This is precisely what I have been trying to get you to answer.

    Is that not what the field perturbations of a S matrix describing?
    field/perturbations generically described as virtual particles and field excitations generically a real particle?
     
    Last edited: Jan 11, 2017
  6. Jan 11, 2017 #166
    Where are you getting incompatible with causality from? Are you ignoring multiparticle system states? Why can't you have a global distribution of field perturbations?

    Which brings us right back to my original post which you called gibberish.

    I reiterate there are no particles only fields. Soeaking of my original post you objected to. What do you call the propogator contributions of field perturbations ie how off shell the particle is
    https://en.m.wikipedia.org/wiki/Propagator

    http://www.google.ca/url?sa=t&source=web&cd=14&ved=0ahUKEwisvJjWzrvRAhXEw1QKHS4xAagQFghOMA0&url=http://www-pnp.physics.ox.ac.uk/~barra/teaching/feynman.pdf&usg=AFQjCNFXFEf7xQrDFKy1hG1mb6SlMwmSKg&sig2=3Ia1ETeyUQaCxwSZR3GFUA

    is the propogator not a plane wave? Yet you stated their is no wavefunction for virtual particles in your reply to my original post.
     
    Last edited: Jan 11, 2017
  7. Jan 12, 2017 #167
    Hi Arnold, I really want to thank you for this article, as I find the topic of the Vacuum (or spacetime) to be truly interesting.

    It was physicist Andrei Sakharov who said "the mysteries of the vacuum will be the great challenge for 21st-century physics"

    But after having read you tell me what I shouldn't believe, I then really want to know what I should believe.
    You've just told me why it's wrong to believe that 6 x 7 = 45 and I hear you on that. But now I want to know what the actual answer is.

    And as far as I can see, you're not explicitly saying "the answer isn't 45" - you're instead saying "we as yet have no reason to believe it's 45"

    So I'm looking for someone to tell me what the Vacuum is actually made out of, if it's not made out of "virtual particles".
     
  8. Jan 12, 2017 #168
    removing all matter a scalar field would be my answer
     
  9. Jan 12, 2017 #169

    A. Neumaier

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    It is made of nothing, it is just a container for real stuff. You could as well ask what the interior of an empty bottle contains.
     
  10. Jan 12, 2017 #170
    Okay, but what is causing/producing the scalar field? There seem to be fluctuations happening in the Vacuum - Black Body radiation indicates this. DeBroglie wavelength of objects also seems to indicate this. So what is that stuff? What is causing these fluctuations/disturbances in the Scalar Field?
     
  11. Jan 12, 2017 #171
    But conceptually, a bottle doesn't need to have black body radiation - the fact that it does says there is something more than the bottle which is there.
    Conceptually, a bottle doesn't need to have a Casimir force inside it - the fact that it does says there is something more than bottle which is there.

    I feel as if you've just told me to ignore that photons have wave characteristics - ie. "just ignore it, this is a mere artifact of observation, and doesn't signify anything"

    I cannot ignore it, I cannot pretend it isn't there - I want to know what's causing it. I want to know if whatever's causing it has its own deeper properties, which perhaps I can't immediately/easily see.
     
  12. Jan 12, 2017 #172

    A. Neumaier

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    The fields are there, all the time. The vacuum state is just the special state of the system where the state is Poincare invariant - timeless, spaceless, due to the symmetry. This is like an empty, infinitely extended container - an abstraction.

    Real spacetime is nowhere a vacuum. it is filled everywhere with fields - gravity, radiation, and traces of matter - with big lumps here and there. These fields are not in a pure vacuum state, however, not even locally, far away from stars and planets.

    If you ask for a cause of that, you need to ask God. The answer is outside the realm of physics.
     
  13. Jan 12, 2017 #173

    A. Neumaier

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    It says that the bottle has an exterior which is not empty, from which the radiation comes. This means that a real bottle is not really empty. The bottle I was talking about was an abstraction, just like the vacuum of quantum field theory.

    So, the effects in an apparent piece of vacuum (apparent since there are invisible fields in any vacuum that can be created experimentally) between pieces of matter are caused by the matter and fields surrounding the vacuum,.
     
  14. Jan 12, 2017 #174

    Sir, I don't wish to invoke a metaphysical explanation, I feel that physics and the scientific method can probe everything usefully.

    Blackbody radiation can be measured reliably, and isn't overly dependent on whatever combination of cosmic events (radiating suns, exploding stars, black holes) may be happening around the rest of the cosmos at the time.
    Casimir force can be measured reliably, and experimental observation of it doesn't give radically different results when done with appropriate experimental rigor.

    Furthermore, the very ideas of waves or particles or fields are themselves concepts we apply onto reality. If I choose to call an automobile a particle, then that's my choice, and as long as I maintain a logical consistency, then I can describe the universe that way.

    Saying that it's wrong to choose to describe Vacuum fluctuations with particles, is like saying it's wrong to describe light using photon particles.
    If the fluctuations of the Scalar Field exist, then there's no reason why the idea of particles can't be adopted to describe it.
     
  15. Jan 12, 2017 #175

    A. Neumaier

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    Black body radiation is caused by the electromagnetic field. Hawking radiation is real particles created by the gravitational field. Nothing is created by either the vacuum or by virtual particles.
    That's the scientific part.

    But you wanted a cause for the field itself, which is metaphysics.
     
    Last edited: Jan 12, 2017
  16. Jan 12, 2017 #176

    What if all matter in the universe is reduced to absolute zero in temperature - will Vacuum Fluctuations cease?
    What if all matter in the universe is removed from spacetime - will spacetime cease to exist, or at least its Vacuum Fluctuations?
     
  17. Jan 12, 2017 #177

    A. Neumaier

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    If you remove all matter from spacetime there will still be the electromagnetic and the gravitational field. But no one to observe it, so no physics.

    Absolute zero is a fiction like the vacuum itself. One cannot reach it, only approach it.

    This has nothing to do with vacuum fluctuations, which are not things happening.
     
  18. Jan 12, 2017 #178

    Sir, I feel your assertion is no less metaphysical than mine. You want to assert that fluctuations are intrinsic to the field, and cannot be conceptually distinguished from it. By the same token, you could also say that energy is an intrinsic property of all matter, and doesn't deserve to be discerned or distinguished from matter. At that point, it does feel like arguing a religious debate.

    Sir, I'm not as immediately concerned with a cause for the field as I am with why it fluctuates and doesn't remain at a mathematical zero.
    Your assertion that it's the presence/influence of other things in the universe that cause the fluctuations, doesn't explain the consistency between the various experimental measurements that have been made over time on these fluctuations, nor does it explain the anisotropic characteristics observed, in spite of matter not being homogenously distributed across the universe.
     
  19. Jan 12, 2017 #179

    A. Neumaier

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    Fields fluctuate because this is a general property of fields. Asking about their causes is as meaningless as asking about why sine waves oscillate. It is because they are defined that way.
     
  20. Jan 12, 2017 #180
    Alright, to use your parlance - would the "minimal background fluctuations in the field" cease to exist under any circumstances?

    It seems like a Chicken-and-Egg argument: Is the Field the basis for the fluctuations, or are the fluctuations the basis for the Field?

    It's like arguing over whether Light is "a particle with wave-like characteristics" versus Light being "a wave with particle characteristics"
     
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